Coronary Artery Bypass Graft

from its surrounding tissue. The tube visible at the bottom is the aortic cannula (returns blood from the HLM ). The tube above it (obscured by the surgeon) is the venous cannula (receives blood from the body). The patient's Heart is stopped and the Aorta is cross-clamped. The patient's head (not seen) is at the bottom.]]

Coronary artery bypass surgery, also '''coronary artery bypass graft surgery''' and ''' Heart bypass''' (colloquial), is a Surgical Procedure performed on patients with Coronary Artery Disease (see Atherosclerosis ) for the relief of Angina and possible improved Heart muscle function. Vein s or Arteries from elsewhere in the patient's body are Grafted from the Aorta to the Coronary arteries, bypassing Coronary Artery Narrowings caused by Atherosclerosis and improve the Blood supply to the Myocardium (heart muscle).

TERMINOLOGY

There are many variations on terminology, in which one or more of 'artery', 'bypass' or 'graft' is left out. The acronym for this type of surgery might therefore be CABG (pronounced 'cabbage'),American Heart Association. Heart Bypass Surgery. URL: http://www.americanheart.org/presenter.jhtml?identifier=4484. Accessed on March 26, 2006. '''CABGs''' (pronounced 'cabbages') or '''CAGS''' (pronounced phonetically).

PROGNOSIS

Prognosis following CABG depends on a variety of factors, but successful grafts typically last around 10-15 years.

COMPLICATIONS

Infection - at site where graft was harvested, chest

Non-union / Malunion of Sternum (breast bone)

Anesthetic Complications - drug reactions (e.g. Malignant Hyperthermia )

Myocardial Infarction due to hypoperfusion or early graft occlusion

Graft failure leading to Myocardial Infarction

Death due to Myocardial Infarction , Stroke , Renal Failure , Sepsis

Acute Renal Failure due to hypoperfusion

Stroke - during reperfusion

Stenosis of the graft (late) - particularily of Saphenous Vein Grafts

Keloid scarring

Chronic Pain - at incision sites

TECHNICAL DESCRIPTION

First, the Sternum is cut down the middle with a special bone saw and the chest opened (a procedure known as "cracking the chest" or a Median Sternotomy ). Depending on a number of factors, the surgeon may decide to place the patient on cardiopulmonary bypass ("on-pump") or use suction-stabilizing devices to hold the heart still while sewing the anastamoses ("off-pump"). Blood Vessel s are harvested from elsewhere in the body for grafting. Sometimes artery end branches supplying tissues near the heart are rerouted to create the Bypass .

CONDUITS USED FOR BYPASS

Typically, the left Internal Thoracic Artery (LITA) (previously referred to as ''left internal mammary artery'' or ''LIMA'') and right internal thoracic artery are used for bypass. If additional bypasses are required the Great Saphenous Vein from the leg is frequently used.

Veins that are used either have their Valve s removed or are turned around so that the valves in them do not occlude blood flow in the graft. LITA grafts are longer-lasting than vein grafts, both because the artery is more robust than a vein and because, being already connected to the arterial tree, the LITA need only be grafted at one end. The LITA is usually grafted to the Left Anterior Descending Coronary Artery (LAD) because of it superior long-term patency when compared to saphenous vein grafts.Kitamura S, Kawachi K, Kawata T, Kobayashi S, Mizuguchi K, Kameda Y, Nishioka H, Hamada Y, Yoshida Y. survival and cardiac event-free rates in Japanese patients with the left anterior descending artery revascularized with internal thoracic artery or saphenous vein graft: a comparative study Nippon Geka Gakkai Zasshi. 1996 Mar;97(3):202-9. PMID 8649330.Arima M, Kanoh T, Suzuki T, Kuremoto K, Tanimoto K, Oigawa T, Matsuda S. Serial Angiographic Follow-up Beyond 10 Years After Coronary Artery Bypass Grafting. Circ J. 2005 Aug;69(8):896-902. PMID 16041156. Free Full Text .

The LAD supplies the left ventricle, the part of the heart that pumps Oxygenated blood around the body, and is the most important for survival. Alternatively, an artery such as the Radial Artery from the arm or Gastroepiploic Artery from the Stomach , may be used in place of a vein.

HISTORY

The technique was pioneered by Argentinian René Favaloro and others at the Cleveland Clinic in the late 1960s.Captur G. Memento for Rene Favaloro. Tex Heart Inst J. 2004;31(1):47-60. PMID 15061628. Free Full Text . Currently, about 500,000 CABGs are performed in the United States each year.

SEE ALSO